1. Field of the Invention
Disclosed is a system for mixing a chemical agent with a carrier fluid and pumping the mixture to a target location. More specifically, a calibration device is incorporated into the suction line of a pump, thereby delivering a predetermined addition of at least one chemical agent into the carrier fluid passing through the pump. Existing pumping devices may be retrofitted to include the subject device.
2. Description of the Background Art
Transferring a diluted chemical agent, via a carrier fluid, onto a selected target often involves mixing a predetermined amount of the agent into a given quantity of carrier fluid within a storage container or reservoir and then pumping the mixture to the desired location. Such a procedure requires time to generate the needed quantity of carrier fluid before the mixing can occur. Further, once the approximate volume of mixture is created any excess quantity must be disposed of in an environmentally safe and legally suitable manner.
A more efficient system, both in time and wasted excess mixture, is an active or dynamic mixing system that does not require a set quantity of carrier fluid, but mixes the chemical agent with the carrier fluid on demand. Further, the active or dynamic mixing process is useful to speed the generally homogeneous combining of the chemical agent into the carrier fluid. For many years numerous inventors have attempted, with very limited success, to harness the inherent pressure of a pumping system to induct chemical agent concentrates into the flow path of a carrier fluid. Such systems include ones employed for spraying insecticides, pesticides, and similar materials.
Current spraying systems often incorporate: a carrier fluid container or reservoir; a pumping system; an overflow or bypass circuit for handling excess carrier mixed with the agent; and a delivery system for placing the mixture on the target. Generally, positive displacement pumps are used in a majority of spraying applications. An inherent problem exists with such spraying systems. In order for a positive displacement pump to function continuously, the constant production of pressurized fluid must be handled. The output must either be routed to the target or rerouted back to the storage reservoir for recycling. As long as the flow is continuous, from the reservoir to the target, such mixing of concentrate works. However, when the mixture is rerouted back to the reservoir the material within the reservoir is enriched in the agent. A separate, second reservoir for receiving the excess mixture is possible, but the fluid mixture in this second reservoir would then need to be delivered or wasted.
Supplied by the subject invention is an alternative to delivering continuously the mixture to the target or recycling to a reservoir. The subject device interrupts the pumping during periods when part of all of the pump's production is no longer being sent to the target. The approach incorporated into the subject device for accomplishing the attenuation of the flow is to include a flow-controlled clutch to modulate or shut off the pump as needed. Further, if the subject device is used with a centrifugal pump a standard technique for frustration of the pump is used to regulated the output pressure or if used with an electric motor the motor is modulated by regulating the on-off period or by employing a standard variable speed control.